Fermentation is when a cell uses sugar for energy without using oxygen at the same time. Yeast is an organism that ferments. When yeast ferments sugar, the yeast eats sugar and makes alcohol. Other cells make vinegar or lactic acid when they ferment sugar.
Types of fermentation [change]
- Ethanol fermentation always produces ethanol and carbon dioxide. It is important in bread-making, brewing, and wine-making.
- Lactic acid fermentation produces lactic acid. It happens in muscles of animals when they need lots of energy fast.